In automation technology, field devices are often used, to serve for measuring and/or influencing process variables. Examples of such field devices are fill-level measuring devices, mass-flow measuring devices, pressure and temperature measuring devices, etc., which, as sensors, register the corresponding process variables, fill-level, flow (e.g. flow rate), pressure and temperature.
Field devices serving, as actuators, to influence process variables include, e.g., valves for controlling flow of a liquid in a section of pipeline or pumps for controlling fill level in a container.
A large number of such field devices are manufactured and sold by the firm, Endress+Hauser.
As a rule, field devices in modern manufacturing plants are connected via fieldbus systms (HART, Profibus, Foundation Fieldbus, etc.) to superordinated units (e.g. control systems or control units). These superordinated units serve, among other things, for process control, process visualization, process monitoring, as well as for tasks such as commissioning field devices. Also falling under the heading “field devices” are, in general, such units (e.g. remote I/Os, gateways, linking devices) as are directly connected to a fieldbus and serve for communication with the superordinated units.
Usually, fieldbus systems are integrated into company networks. In this way, process and field device data can be accessed from different areas of an enterprise.
For worldwide communication, company networks can be connected also with public networks, e.g. the Internet.
Modern field devices often exhibit a standardized fieldbus interface for communication with an open fieldbus system and/or a proprietary interface for manufacturer-specific communication with a service unit. Frequently, the service units are portable small-computers (laptops, Palms, etc.), such as are generally known from the field of consumer electronics (office and home computers).
Increasingly users also desire radio servicing of field devices. This applies particularly to field devices arranged in relatively inaccessible locations in an automated facility. Over a radio connection, the user can service these field devices easily and comfortably.
For this reason, it is conceivable that field devices be equipped with a radio interface, which can communicate wirelessly with an appropriate service unit (e.g. laptop, Palm, etc.).
A known standard in the field of wireless communication is the Bluetooth standard, which is often used in consumer applications.
Bluetooth modules available to this point in time report in a radio network using a predetermined, fixed identifier.
It would be conceivable to equip field devices with a Bluetooth module.
A service unit would automatically recognize the Bluetooth module and show the identifier of the Bluetooth module on the screen of the service unit. Via this identifier, the user could select the pertinent field device. For the user, however, it would be extremely disturbing to have to associate the identifier of the radio module with a particular field device, in order to be able to service the pertinent field device. This associating can lead to mixups and thus cause service errors.
Radio modules permanently connected with the field device make the device expensive. The retrofitting of existing field devices would likewise be very complex and expensive.